Best thing to do with those old Facebook fights is just let them sit there like a crockpot. My cousin and his brother in law went at it over green bean casserole for three days straight one year, then nobody said a word until the next holiday when they acted like it never happened. Deleting it robs everybody of the payoff. The four month later "it's jelly" reply is comedy gold and that guy knows exactly what he did. Let the internet do its thing.